Leave the bottle... how does that work

[Crafter_Man]

Same topic from 2001:

Old Western saloons--Giving the customer the whole whiskey bottle with the glass

You know how in all those Western movies the man walks into the saloon and orders whiskey. The barkeep puts the whole bottle in front of him and then the customer pours his own drinks. Was that the usual custom before Prohibition? Are there now specific laws against serving alcohol in this way, or is it just a custom that went out of style?